Edit: Added some more photos to the bottom. Those were taken with the curtains shut. Also took a short video.
Finally completed the zodiac display. Aside from the sickly colour of the top and 1 of the red LEDs stopped working after I glued it all together, I`m pretty happy with the way it turned out.
It`s made of 4 layers of 5mm foam board. It uses 2 2mm clear acrylic layers for the lights with a sheet of red between them. The red hides the scratches of the star connections but doesn`t interfere with the red LED when switched on. Around the edge where the acrylic touches the foam I put aluminium tape to help reflect the light back into the middle. If you think the constellations look weird it`s because they are mirrored. I copied them straight onto the plastic and then had to flip it over because the best effect is when the scratches are on the underside. Oh well, the kids won`t know.
I forgot to take some pics inside before sealing it up but it`s pretty simple to image.
Originally I glued a pack of 4 AAA NiMH together and sealed it inside with the 2 screw heads as charging terminals. Unfortunately the first time I charged it the heat made the hot glue soft and the batteries lost connection :/ I added the battery pack through the bottom but I still charge with the screw heads and some magnets on wires.
The left hand side slides out so that I can get access to the plastic sheets. I may add more info onto the middle red sheet, like the earth\sun thing later.
A little recess on all edges holds it all in.
2 microswitches turn on the layers seperately.
In the dark - off.
Bottom layer only. 1 LED stopped working thats why the right side is brighter.
Top layer only.
Both layers - close up.
The 3 plastic sheets used. From left to right - red middle sheet, clear bottom sheet, clear top sheet. Ignore the purple, it`s just there to make the clear sheets visible.
The first video is mine. The 2nd and 3rd show what kind of stuff is possible with edge lighting.
https://www.youtube.com/watch?v=zq5ntcP2mmM
Really would like to see a
Really would like to see a video of this as I’m not completly sure of what you have built - except that it looks pretty nice! 
Video is doable, I better
Video is doable, I better charge the camera though.
Its called edge lighting. It can be used for lots of things. Basically the "stars" are lit blue and the connecting "lines" are lit red but not from behind. I could cut the back out of it and it wouldnt affect how it operates at all (but it wouldnt be held together very well). The light is shining on the edge of the clear plastic. The light is internally reflected in the plastic, meaning it doesnt come out of the plastic and become visible until it hits an imperfection in the plastic like my stars and lines. When it does the light escapes the plastic and we can see it.
If the structure had been made out of something more solid than foam I could have left the entire thing without a back.
wow… bright!
Ingenious! and glorious too - (I noticed the constellations were reversed ;))
So you have four layers - one has stars that are illuminated with white light, one has the zodiac lines that are illuminated with red… What do the other two layers do?
The traces are much brighter than i expected, how many leds are you using - and how have you distributed them around the acrylic?
Yeah I expected you to see
Yeah I expected you to see something weird 
Theres only 2 layers of acrylic but 4 layers of foam board, 2 extra for the back and front. I thought of adding a 3rd lit layer for labels or something cool like a giant sun but didnt bother.</p><p>Actually it even surprised me too. The red layer DID have 2 LEDs at the top but 1 stopped working so now its only running on 1. It still shows up pretty good but its noticably lopsided. I used <a href="http://akizukidenshi.com/catalog/g/gI-01444/">these </a>RGB leds. The blue layer has 3 SMD LEDs on the right hand side. I cant remember where I got them, but theyre bright enough to hurt your eyes looking dead on. I toned down the led current to about 20mA so they wouldnt get so hot and melt something.
This is brilliant and looks
This is brilliant and looks really cool! Well done!
Would love to see a video of it in action
Cool!
That looks pretty cool.
How do you get the stars in the constellations to light up light blue while all the regular stars are dark blue?
I just made the holes a lot
I just made the holes a lot smaller
The large stars are done with a 1mm drill bit, the small ones were just the pointy end of a compass.
